It is well known that conventional lawn mowers has the potential of inflicting great bodily harm or loss of life to the operator or nearby person. The metallic cutting blade customarily used in lawn mowers can permanently disfigure, or injure the operator or an innocent bystander. There are several situations where this may happen. For example, if the operator should slip and fall, a part of his body, such as a foot or an arm, may accidentally get underneath the lawn mower with grave consequences. In a case involving a self-propelled lawn mower, loss of control by the operator might cause the lawn mower to run away from the operator and injure another person. Lawn mowers are also known to have started on their own without any warning. For example, an operator cleaning under the lawn mower housing or fixing the blade might be injured when, without any warning, the lawn mower starts on its own. There are also cases where the operator or a nearby person has been hit by projectiles such as rocks, bottles, pieces of wood, etc., propelled by the lawn mower blade. Furthermore, lawn mowers are sometimes subjected to abuse wherein it is put to use for which is not intended, creating potential hazard to the operator. A case like this might involve the operator bodily lifting up the lawn mower and using it as a hedge trimmer.
To make the lawn mower safer to use, flexible cutting filaments have been used to replace the standard metallic blades. Use of flexible cutting filaments, however, has resulted in reduced cutting power, since the flexible cutting filaments have typically round cross-section. Where the filaments have angular cutting edges, the filaments tend to shift in their holder, which in most cases, result in having their cutting edges oriented away from the vegetation being cut. Also, rotary members used for holding the flexible cutting filaments typically include rigid arms or projections which have the potential of hurting or injuring an unwary operator or bystander.